Early investigations directed at isolation of antineoplastic constituents from marine sponges initially led to the geodiastatin proteins and later to a series of pyrrolactams. More recently, other promising leads have been detected in the Porifera phylum, including antineoplastic peptides. To date, only a few new amino acids, peptides and antineoplastic substances have been isolated from marine sponges. One of the Hymeniacidon sp. (Demospongiae Class) which was collected in Palau in 1979 yielded aqueous 2-propanol-methylene chloride extracts which demonstrated a 30% life extension against the U.S. National Cancer Institute's murine P388 lymphocytic leukemia (PS system). Bioassay directed isolation using the PS leukemia data led to isolation and identification of a new cytostatic peptide, herein denominated designated "Hymenistatin 1". The cyclo-octapeptide was isolated and subjected to structural elucidation.
In the continuing effort to locate and define various natural and synthetic substances for treatment of one or more varieties of cancer, research chemists continue to look at natural flora and fauna in an attempt to isolate and identify new substances which exhibit tumor growth inhibitory or antineoplastic activity while minimizing, if not totally eliminating, some of the severe side effects accompanying known chemotherapeutic agents.
It is in the further pursuit of these goals that marine species heretofore ignored are now being examined to determine whether they contain constituents which, when isolated, will exhibit useful biological properties such, for instance, as inhibiting tumor growth.
Accordingly, a principal object of the present invention is to provide new agents which possess useful biological properties.
Another object of the present invention is to provide methods and procedures for isolating antineoplastic substances from marine life in a form whereby they may be readily and usefully employed in the therapeutic treatment and management of one or more types of cancer which occur in human hosts and are manifested by malignant tumor growth.
A further object of the present invention is the provision of unique means and methods of isolating and elucidating the structure of a new cyclo-octapeptide from the South Pacific sponge Hymeniacidon sp.
These and still further objects of the present invention as shall hereinafter appear are readily fulfilled by the present invention in a remarkably unexpected manner as will be readily discerned from the following detailed description of exemplary embodiments thereof.